The proposal of study approved by the investigators institutional review boards and institution's ethical committee, and all participants will sign a written consent before enter to study. A total of 300 infertile women undergoing sonohysterography will be randomized to intrauterine or intracervical balloon catheter placement. The examination is scheduled in the early follicular phase of menstrual cycle, immediately after cessation of menstrual flow and before day 10. After preparation of patient, a 2 lumen 6-French flexible catheter is introduced into the cervical canal and balloon at the catheter tip is placed in the lower uterine segment or 1 cm into cervical canal and inflated with 1 mL of sterile saline solution. Under sonographic guidance, sterile normal saline solution (10-50 mL) is slowly introduced into the cavity until an adequate distention of the uterine cavity is obtained. Three-dimensional ultrasound scanned volumes are recorded. Patients are asked to assess their level of pain at the time of the balloon inflation and deflation using a 10-point visual analog pain scale. Patients are checked for the sign and symptoms of vasovagal reaction during and 30 minutes after procedure. Outcome measures will be assessed based on the intent-to-treat principle.